For the first time, migratory birds marked with satellite transmitters were tracked during an outbreak of highly pathogenic H5N1 avian influenza virus (H5N1) in Asia, providing evidence that wild birds may be partly responsible for the spread of the virus to new areas. In the study, scientists from the USGS Alaska Science Center and the University of Tokyo attached satellite transmitters to 92 northern pintail ducks several months before the H5N1 virus was discovered in dead and dying whooper swans at wetlands in Japan.? They found that 12 percent of marked pintails used the same wetlands as infected swans and that pintails were present at those sites on dates the virus was discovered in swans